Add and check transcode nodes

Silo is in active development before 1.0. These guides are updated frequently.

A single Silo server already streams and converts video itself. Add nodes when you want part of that work on other machines. Every node runs the same Silo image in a different mode and shares the main server’s PostgreSQL, Redis, and encryption key.

Choose a node type

Type	Does	Use it when
Transcode	Converts video for playback and prepared downloads	The main server’s CPU or GPU can’t keep up, or another machine has a better GPU
Proxy	Delivers streams and downloads to clients	You want streams to leave from somewhere other than the main server, such as a host with more bandwidth

Transcode nodes only talk to the main server and proxy nodes, so they need no public address. Clients connect to proxy nodes directly.

Prepare the node

The server repository’s Compose file includes commented silo-proxy and silo-transcode examples. Use them as a starting point on the node’s host. A node needs:

• MODE=transcode or MODE=proxy.
• NODE_NAME, the same name you give the node in Silo, and NODE_URL, the node’s own address. Silo matches the running node to its entry by these values.
• The same SECRET_KEY as the main server, and DATABASE_URL and REDIS_URL pointing at the shared PostgreSQL and Redis.
• The media mounted at the same container path the main server uses, such as /mnt/media.
• A plugin directory (SILO_PLUGIN_CACHE_DIR). A transcode node also needs the artwork directory and a writable transcode directory with plenty of free space.
• For GPU encoding on a transcode node, its own driver and device access, set up as in Set up transcoding.

The examples publish the node on port 8082 (transcode) or 8083 (proxy). The default Compose file publishes PostgreSQL and Redis only on the main host’s loopback address, so a node on another machine can’t reach them until you change that. Keep PostgreSQL, Redis, and node ports on a trusted network.

Local artwork on the main server isn’t shared with other hosts automatically. For several hosts, consider S3 artwork storage.

Add the node

Add the node in Silo, then start it.

1. Open Admin > Nodes and select Add Transcode or Add Proxy.
2. Enter a Name that matches the node’s NODE_NAME.
3. Enter the URL the main server uses to reach the node, matching its NODE_URL. A private address is fine.
4. For a proxy node, enter a Public URL if clients should use a different address, such as a public hostname in front of the node. Leave it empty to give clients the URL, which then must be reachable from clients.
5. Optionally set Max Transcodes or Max Streams (and Max Egress Bandwidth (Mbps) for a proxy), then select Save.
6. Start the node with its Compose file.

Silo checks every node every 30 seconds. The node’s state changes to Healthy once Silo can reach it, and a transcode node’s Acceleration block shows the verified encoder, such as VAAPI or SW. Use the refresh button to check it right away.

Then play something that needs conversion, or from a client that uses the proxy. Admin > Activity shows the session, and the node’s Capacity block shows the job. Test seeking and stopping as well.

Route playback to nodes

Node routing in Admin > Settings > Playback decides where remuxing and transcoding run and which machine sends each stream to the client. Silo Defaults prefers transcode nodes for conversion and proxy nodes for delivery, and falls back to the main server. GPU offload keeps direct play and remuxing on the main server and sends video transcodes to nodes. Central egress runs conversion on nodes but sends every stream from the main server. A setting ending in “only” never falls back, so that kind of playback fails while no healthy node of the needed type is available.

If work does not reach the node

Check that the node is enabled, Healthy, below its limit, and can read the file at the same path. A transcode node whose transcode disk is 95% full is skipped while another node has room; free up space on the node itself.

Maintain a node

Turn a node’s switch off to stop new work while current sessions finish. After changing its driver or devices, use Re-probe; Silo refuses it while the node is transcoding. See Set up transcoding.

Update all nodes together with the main server when the release notes say so. During the 1.0 update, don’t mix alpha and 1.0 nodes.